Le Professeur Morten Iversen, Institut Alfred Wegener pour la recherche polaire et marine & MARUM – Centre des sciences environnementales marines de l’université de Brême, fera un séminaire le 16 octobre 2025 à 13:00 dans l’amphithéâtre OCEANOMED sur le thème : The Living Carbon Pump: From Microbial Aggregates to Global Carbon Sequestration.
Short Abstract
The ocean’s biological carbon pump moves biologically fixed carbon from the surface to the deep sea, maintaining the vertical gradient in oceanic carbon. This seminar explores how tiny particles, called marine snow, and the microbes that colonize them control carbon breakdown and nutrient recycling. We will see how small animals like zooplankton feed on and fragment these particles, shaping how much carbon sinks. From local interactions to global patterns, I will highlight how changes in plankton communities and particle composition affect carbon export and nutrient recycling. The biological carbon pump has been very resilient to ecosystem change, but will it remain so as Earth’s climate continue to change.
Detailed Abstract
The ocean’s biological carbon pump maintains the vertical gradient of carbon in the ocean by linking microbial processes on sinking particles with global carbon sequestration in the deep sea. This seminar will explore the mechanisms driving the biological carbon pump across scales – from microscale particle colonization to large-scale ecosystem shifts. We will examine how aggregate morphology and small-scale fluid dynamics determine where and how microbes attach to marine snow, influencing nutrient recycling and carbon export. Building on this, we will discuss how zooplankton feeding, repackaging, and fragmentation modulate particle flux attenuation in the upper ocean, shaping both the strength and depth of the carbon pump. At larger spatial scales, climate-driven changes in plankton communities, particle composition, and trace-metal recycling are altering the biological carbon pump’s capacity to sequester carbon. Our research highlights the need to better understand how the organic composition of settling aggregates evolves as they degrade and age through the water column, and how zooplankton and microbial activity drive nutrient regeneration and transformation between dissolved and particulate organic matter. The biological carbon pump is a living, dynamic system and its future role in Earth’s climate will depend on how these interacting biological and biogeochemical processes respond to a changing ocean.